BIODIVERSITY OF SAGO (Metroxylon spp.) AND ITS UN- DERSTORY IN MALUKU, Indonesia

Sago (Metroxylon spp.) is an important crop in Maluku. This study aims to identify the biodiversity of sago palm and understory vegetation around sago clumps in Maluku. The research was carried out in six sago area from September 2015 to October 2016. The Sago Plant identification was carried out through the growth phase of sago, i.e. seedlings, saplings, weaning, trunks, and ripening. Vegetation observation was done in radius 100 m2 surrounding sago clumps. The result shows that Metroxylon rumphii Mart type. (Tuni sago), M. sagus Rottb. (Molat sago) and M. Silvester Mart. (Ihur Sago) dominates sago palms area in Seram and Ambon Islands, Maluku. There are significant morphological differences between the types of sago, especially in stem height, midrib width, leaf midrib colour, number of thorns, and flower stalk length, as well as the difference of carbohydrate content. Understory vegetation of each observation sites diverse consist of 15 families and 20 species. The families that dominate the vegetation under the sago palms are Araceae, Thelypteridaceae, and Athyriaceae. The types of plants from Araceae are taro types and broadleaf, while those from the Thelypteridaceae and Athyriaceae families are types of ferns.


Introduction
Sago (Metroxylon spp.) is an important socio-economic crop in Southeast Asia [1], where the centres of sago diversity originating from Papua New Guinea and Maluku [2]; [3]; [4]. Sago is known as a plant that can grow and thrive in various ecologies, such as in swamps area [5], acidic peat soils, saline and submerged soils [3]; [6]. This plant resistant to flooding, drought, fire and strong winds due to strong fibrous roots. Stuck in the mud.
Sago is the main source of carbohydrates for the people of Eastern Indonesia, especially in Papua and Maluku. The total area of sago in Indonesia in 2018 reached 311,964 ha, and the largest area of sago is in Papua province (155,943 ha), while the area of sago in Maluku is in third place, which is 36,484 ha. In terms of productivity, sago palms have higher productivity than other carbohydrate-producing crops, such as sweet potato, corn, rice and cassava. However, until now the production is still very low because most of it is still in the form of natural sago forests that have not been properly cultivated, and only plants that are easily accessible are harvested.
Sago palm grows in swampy, alluvial and peaty soils where almost no other major crops can grow without drainage or soil improvement [7]; [8]. Sago palm is one of the most important bioresources for not only sustainable agriculture but also rural development in swampy areas of the tropics. However, Metroxylon palms, even sago palm is recognized as an unexploited or underexploited plant because this species has been harvested from natural forests and/or has been semi-cultivated under very simple maintenance.
analysis, the species frequency (F), the frequency of the i-th species (F-i), and the relative frequency of the i-th species (FR-i) can be calculated using the following formula:

Distribution and Diversity of Sago Type
The distribution of sago in Maluku spreads throughout coastal areas, rivers and medium lowlands at altitude 700 m above sea level, even though this plant is found at the altitude 1000 m above sea level. However, [12] reported that sago growth might be slower at an altitude higher than 400 m asl. Sago grows well in tropical lowland humid areas. The optimum conditions for growing sago are at a minimum temperature of 26 oC, relative humidity of 90%, and light radiation of 9 MJ/m2 per day [6]. Sago is also found grows in the saline area [13]; however, the salinity not exceed 10 S/m [10]; [11].
Based on the distribution, we choose six sago forest at six villages representing distribution and diversity of sago type in Maluku. There are five types of sago that are found and dominate the sago area on Seram and Ambon islands, namely M.  [14] reported significant morphological differences between the five types of sago, especially in stem height, midrib width, leaf midrib colour, number of thorns, and flower stalk length. The stems of Tuni sago, Molat sago, Ihur sago, Makanaru sago, and Rattan sago are 25 m, 16 m, 20 m, 10 m and 9 m, respectively, while the width of the base of the fronds is 25 m, 20 m, respectively. 19 m, 8 m and 20 m. M. rumphii Mart type. (Tuni sago) has fewer saplings, drooping tips of the leaflets are more regular and rarely grows around the main tree. Ihur sago species have more tillers, grow irregularly, the tips of the leaves are upright, and many tillers grow around the main tree. The appearance of each growth phase of sago for the five types of sago found in Maluku during the dry and rainy seasons ( Table 1).
The five types of sago also contain different carbohydrates. [15] reported that the carbohydrate content in Tuni Sago, Molat sago and Sago Ihur were respectively 89.13%, 88.6% and 76.03%, while two others are lower. Therefore, economically, these three types of sago are more widely used and processed by the community [16].  Table 1 Average of plant height, number of midribs, and stem diameter of sago palm during rainy and dry season in Maluku.

Understory Vegetation of Sago Palms
The results of vegetation identification under sago stand in the six observation sites are shown in Tables 2, 3 Table 2 describes the number and types of vegetation understorey of sago palms in Ariate Village, which 21 types of vegetation from 15 families were found. This family of vegetation grows well under shade conditions. Some of the vegetation found is beneficial for humans, but there are also plants that interfere with the growth of sago. Several types of plants, such as Typhonium flagelliforme L, Piper betle L, and Cissus sicyoides L are known as medicinal plants [17]; [18]; [19]. Pandanus amaryllifolius Roxb is widely used for cooking spices [20], while Etlingera coccinea (Blume) S. Sakai & Nagam is known as a plant that produces essential oils [21]. Cissus sicyoides L is a weed that interferes with the growth of sago.
According to the important value index of vegetation, during the dry season, more vegetation plays an important role in maintaining ecosystem stability, such as Christella parasitica, Etlingera coccinea (Blume) S. Sakai & Nagam, Typhonium flagelliforme L, and Bridelia sp. Willd. In the rainy season the importance value index changes, where Typhonium flagelliforme L and Bridelia sp. Will has a higher IVI than Christella parasitica and Etlingera coccinea (Blume) S. Sakai & Nagam. Other vegetation has lower relative density and IVI values, both in the dry season and the rainy season.  Source of primary data The relative density of each type of vegetation is related to the morphological characteristics of the vegetation, such as plant height, sunlight requirements and their habitat. Large trees vegetation is generally lower in density than shrub vegetation. This situation is in accordance with the findings of [22], where the small vegetation that makes up the ecosystem tends to be denser than the large trees.  Tables 3, 4 [22] reported that natural ecosystems tend to have a high number of vegetation types, on the other hand, damaged ecosystems experience a decrease in the number of vegetation types Understory vegetation of sago palms dominated by three vegetation families, namely Araceae, Thelypteridaceae, and Athyriaceae. Types of plants included in the Araceae family taro and broadleaf plants, while Thelypteridaceae and Athyriaceae are ferns. The understory vegetation plays an important role in forest conservation and nutrient availability and is also an important component in forest aesthetics [23]. The vegetation structure includes 1) vertical vegetation structure, classifies the layers of vegetation largely according to the different heights to which their plants grow, i.e. tree layers, poles, weaning, seedlings, and herbs that makeup vegetation, 2) horizontal distribution which describes spreading of each vegetation, and 3) the abundance of each species in a community [24]. It seems that the observation site has different type and structure of vegetation.
The analysis of the vegetation index value obtained is important quantitative information about the structure and composition of a plant community. Quantitative estimation of vegetation communities consists of 1) estimating the composition of species vegetation in an area compared to other areas, or the same area with different observation times, 2) estimating the diversity of species within an area and 3) correlating vegetation diversity with certain environmental factors [25]; [26].
Quantitative parameters in plant community analysis include density, frequency, and dominance. The various types of plants that are dominant in the community can be identified by measuring dominance. Dominance measures can be expressed by several parameters, including biomass, crown cover, basal area, and important value index (IVI) [27]; [28]; [29]. The fern species Christella parasitica (L.) Lev had a relative density of 26.80 and IVI of 34.69, which the highest compared to other vegetation types both in the rainy and dry seasons. Etlingera coccinea (Blume) S. Sakai & Nagam, Bridelia sp. Willd, Typhonium flagelliforme L., Colocasia sp., Diplazium dietrichianum (Luerss.) C. Chr., and Colocasia esculenta L., are also common vegetation types found in the sago area. Cissus sicyoides L., is known as medicinal herbal, however because of its growth character, this plant interferes sago growth. Source of primary data

Source of primary data
The results showed that ferns more dominance than other species, which is shown by its density, frequency, and Importance Value Index (IVI). The Important Value Index is an index that describes the importance of the vegetation in its ecosystem. The higher the value of IVI index, the greater the vegetation type affect the stability of the ecosystem. The Importance Value Index (IVI) can be used to determine the dominance of plant species over other plant species [25]. There are significant morphological differences between the types of sago, especially in stem height, midrib width, leaf midrib colour, number of thorns, and flower stalk length, as well as the difference of carbohydrate content.

Metroxylon rumphii
Understory vegetation of each observation sites diverse consist of 15 families and 20 species. The families that dominate the understory vegetation of sago palms are Araceae, Thelypteridaceae, and Athyriaceae. The types of plants from Araceae are taro types and broadleaf, while those from the Thelypteridaceae and Athyriaceae families are types of ferns. Several types of plants, are known as medicinal plants, used for cooking spices, and produces essential oils plants.